"We lost friends who can no longer talk to us who are still in the organization," Remini, 43, told DeGeneres. "But we have other friends, who are not in the church, who have stood by us and that's all we can ask for."

Remini became involved with Scientology at a young age because of her mother's affiliation.

"So it's all we really knew," Remini said. "But over time, my eyes got opened and I could just no longer be affiliated with the organization, and my family felt the same, so we left."

Remini confirmed in July that she had left the church founded by science fiction writer L. Ron Hubbard in 1954. Actors John Travolta and Tom Cruise are among famous members.

Scientology followers believe humans are immortal beings whose experience extends beyond one lifetime. Critics have called the religion a cult.

"It all began when Leah questioned the validity of excommunication of people," the source said. "She is stepping back from a regime she thinks is corrupt. She thinks no religion should tear apart a family or abuse someone under the umbrella of 'religion.' "

Remini also talked with DeGeneres about her upcoming stint on ABC's "Dancing With the Stars."

She said she hurt in "places I didn't know could hurt. ... It's so much harder than I thought, and most people do say that, but it's true."